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  Method of making a coated medical deviceUSPTO Application #: 20060030936Title: Method of making a coated medical device Abstract: Medical devices, such as stents, having a surface, a coating layer comprising a polymer disposed on at least a portion of the surface, and a composition comprising a biologically active material injected into or under the coating layer at one or more locations in the coating layer to form at least one pocket containing a biologically active material are disclosed. The composition may be injected using a nanometer- or micrometer-sized needle. Methods for making such medical devices are also disclosed. Using this method, a precise amount of the biologically active material may be disposed accurately and efficiently on the medical device at predefined locations. (end of abstract) Agent: Jones Day - New York, NY, US Inventors: Jan Weber, Gordon Kocur, Michael Helmus, Maria Palasis USPTO Applicaton #: 20060030936 - Class: 623001420 (USPTO) Related Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Arterial Prosthesis (i.e., Blood Vessel), Drug Delivery The Patent Description & Claims data below is from USPTO Patent Application 20060030936. Brief Patent Description - Full Patent Description - Patent Application Claims
1. FIELD OF THE INVENTION [0001] This invention relates generally to medical devices for delivering a biologically active material to a desired location within the body of a patient. More particularly, the invention is directed to a method of a making a coated medical device by disposing a coating layer on the surface of the medical device and injecting precise amounts of a biologically active material into or under the coating layer. 2. BACKGROUND OF THE INVENTION [0002] It has been common to treat a variety of medical conditions by introducing an insertable or implantable medical device such as stents, catheters or vena cava filters having a coating for release of a biologically active material into a body lumen of a patient. For example, various types of drug-coated stents have been used for localized delivery of drugs to a body lumen. See, e.g., U.S. Pat. No. 6,099,562 to Ding et al. Such coatings are generally manufactured by pre-mixing the drug with a dissolved polymer and using a spraying method or a dip coating method to deliver the mixture to the surface of the medical device. To spray the drug mixture, the drug must be well dispersed through a polymer coating mixture. [0003] Also, because the drug or biologically active material can only tolerate a certain range of temperatures, the temperature at which the coating is dried or cured is restricted by the presence of the drug or biologically active material in the coating. More specifically, if the drug or biologically active material has a maximum temperature tolerance of 50.degree. C., the polymer coating containing such drug or material should not be dried or cured above this temperature. Therefore, an application of a coating formulation that contains both a drug or biologically active material and polymer to a medical device can limit the temperature at which the coating is dried or cured and increase the amount of drying time required. [0004] When a drug whose dosage must be strictly controlled is contained in the coating of such medical device, the amount of coating present on the medical device must be accurately adjusted. Previously, the only way to adjust the amount of coating on a medical device was to control the process parameters used to apply the coating composition onto the surface of the medical device to form the coating, such as controlling the application or spraying time and the flow rate of the coating solution. An improved method to manufacture a coated medical device having a strictly controlled amount of drug is needed. [0005] In the conventional methods for coating medical devices, such as spray-coating or dipping, an entire surface or all surfaces of the medical device are coated even though it may be desired that only part of the surface is coated, or only some of the surfaces are coated. For instance, in medical devices having a tubular portion, such as a vascular stent, the inner surface of the tubular portion does not need to be coated with a coating containing a biologically active material that is used to treat only the body lumen wall that contacts the outer surface of the stent. When the entire outer surface of a medical device contains a biologically active material, this biologically active material can be delivered to both tissues in need of treatment, such as lesions and healthy body tissue. [0006] Also, with existing coated medical devices, generally, the coating is uniformly applied along the entire length of the device or surface of the device. For example, conventional coated stents are coated uniformly along the entire length of their surface. By having the device uniformly coated along its length, the concentration release profile of the biologically active material along the length of the coated surface may be in the shape of a bell-curve, wherein the concentration of the biologically active material released at the middle of the surface is greater than the concentration of the biologically active material released at the ends of the coated surface. [0007] Accordingly, there is a need for coated medical devices where the biologically active material can be positioned in predefined or selected regions of the medical device. Accordingly, there is a need for a method of applying a drug to the surface of a medical device. Also, there is a need for a method of making a coated medical device having a precise amount of a drug at predefined regions on the device and having a coating with a desired release profile. 3. SUMMARY OF THE INVENTION [0008] These and other objectives are accomplished by the present invention. The present invention provides a method of making a medical device having a surface, wherein at least a portion of the surface is covered with a coating layer. This method comprises disposing a coating formulation comprising a polymer on at least a portion of the surface to form the coating layer. This method further comprises injecting a composition comprising a biologically active material into or under the coating layer at one or more locations to form at least one pocket containing the biologically active material. Preferably, the drug composition is injected into the coating layer using a micrometer- or nanometer-sized needle. [0009] The present invention also provides a method of making a coated stent having a surface, wherein at least a portion of the surface is covered with a coating layer. In this embodiment, the method comprises providing a stent having a surface and disposing a coating formulation comprising a polymer on at least a portion of the stent surface to form a coating layer. The coating layer is substantially free of any biologically active material. The method also includes injecting a composition comprising a biologically active material into or under the coating layer using a micrometer- or nanometer-sized needle. The composition is injected into or under the coating layer at a plurality of locations to form a plurality of pockets containing the biologically active material. [0010] The present invention further provides for a method of making a medical device having a surface, wherein at least a portion of the surface is covered with a coating layer. This method comprises disposing a first coating formulation comprising a first polymer on at least a portion of the surface to form a first coating layer, wherein the first coating layer is substantially free of any biologically active material. The method also comprises injecting a first composition comprising a first biologically active material into or under the coating layer, wherein the first composition is substantially free of a polymer. The first composition is injected into or under the coating layer at a plurality of locations to form a plurality of pockets containing the first biologically active material. This method may further comprise forming an additional coating layer by disposing a second coating formulation that comprises a second polymer over the first coating layer. [0011] The present invention provides for an efficient, safe, and accurate method of manufacturing a medical device by depositing a precise amount of a biologically active material into a coating layer on the surface of the medical device at predefined locations to obtain a desired release profile of the biologically active material. Depositing desired amounts of a biologically active material at pre-defined locations is cost-effective because only necessary amounts are applied and the patient is exposed to necessary dosages of the biologically active material. The present method allows for the biologically active material to be applied to the medical device as a final step in the manufacturing process such as after the stent has been crimped on a balloon catheter. Thus, this method minimizes the risk of loss of the biologically active material and an operator's exposure to the biologically active material. Because the biologically active material is applied after the formation of the coating layer, the temperature at which the coating layer can be processed is not limited by the temperature tolerance of the biologically active material. 4. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 is a cross-sectional view of a portion of a medical device of the present invention showing a medical device having a surface, a coating layer on the surface, and pockets containing a biologically active material on the surface of the medical device. [0013] FIG. 2 is a cross-sectional view of a portion of a medical device of the present invention showing a medical device having a surface, a coating layer on the surface, and a plurality of pockets containing a biologically active material disposed in the coating layer at different depths. [0014] FIG. 3 is a cross-sectional view of an individual strut of a stent. The strut has a surface, a coating layer disposed thereon, and a plurality of pockets containing a biologically active material on the surface of the strut. [0015] FIG. 4 is a cross-sectional view of a portion of a medical device of the present invention showing a medical device having a surface, two adjacent coating layers on the surface, and a plurality of pockets containing a biologically active material disposed in both coating layers. [0016] FIG. 5 is a plan view of a cross-sectional view of two coating layers, each having a plurality of pockets containing a biologically active material dispersed therein. The biologically active material in each coating layer is different. [0017] FIG. 6 is a cross-sectional view of a portion of a medical device of the present invention showing a medical device having a surface, a first coating layer disposed on the surface, a second coating layer disposed on the first coating layer, and a plurality of pockets containing a biologically active material disposed within both coating layers. [0018] FIG. 7 is a cross-sectional view of a portion of a medical device of the present invention showing a medical device having a surface, a coating layer on the surface, and a plurality of pockets containing a biologically active material disposed in the coating layers. The pockets contain different biologically active materials. 5. DETAILED DESCRIPTION OF THE INVENTION [0019] The method of the present invention includes providing a medical device having a surface adapted for exposure to body tissue of a patient. FIGS. 1-7 show a portion of a medical device 10 with a surface 20. Generally, the medical device can be inserted into and implanted in the body of a patient. For example, suitable medical devices include, but are not limited to, orthopedic, dental, cosmetic, cardiac, and vascular implants. More particularly, medical devices suitable for the present invention include, but are not limited to, stents, surgical staples, catheters, such as central venous catheters and arterial catheters, guidewires, cannulas, AV shunts, pacemakers, cardiac pacemaker leads or lead tips, cardiac defibrillator leads or lead tips, implantable vascular access ports, blood storage bags, blood tubing, vascular or other grafts, intra-aortic balloon pumps, heart valves, cardiovascular sutures, total artificial hearts and ventricular assist pumps, and extra-corporeal devices such as blood oxygenators, blood filters, hemodialysis units, hemoperfusion units and plasmapheresis units. Continue reading... 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